What should I do about him?

My boyfriend and I have been together for a year and a half, it was great in the beginning... but since about three months ago, he's been starting arguments about nothing. I suffer with anxiety and depression, recently I was told that my granddad has been diagnosed with lung cancer and that he hasn't got long left, this triggered my depresion and my boyfriend does not understand it at all - i've tried to explain anxiety and depression to him multiple times but he doesn't understand still. I want to break up with him, but as it is exam season I feel as though that would be a wrong thing to do, I don't want him to fail his exams because of me. But being with him triggers my anxiety too much and its affecting my exams now, because I'm so upset and anxious all the time - what should I do?